Chapter five of Crucible of Pueblos brings us to Chaco Canyon and the surrounding area. This is an area of particular interest for me, and I presume for most readers of this blog as well. While the rise of Chaco in the tenth and early eleventh centuries AD was clearly a development rooted in earlier events, there has long been less information available for the area of Chaco itself than for the areas to the north that have seen extensive relatively recent excavations of sites dating to the Pueblo I period. The Pueblo I occupations of those areas, the subjects of the earlierchapters in this book, are now fairly well understood, although there of course remain a lot of questions and gaps to fill. Further south the picture is still much murkier.

This chapter is written by prominent Chaco specialists Tom Windes and Ruth Van Dyke, and is particularly important and useful because it includes the first published synthesis of the work Windes has been doing for many years to identify sites in and around Chaco dating to the Pueblo I period. This work was written up as part of the series of reports on the work of the Chaco Project, but that report, dated 2006, remains unpublished. I presume that this is a deliberate decision on the part of the National Park Service to keep sensitive information on site locations from becoming public (although I don’t actually know for sure). This chapter, then, appears to serve as the published record of this important work, which significantly alters the conventional interpretation of Pueblo I in Chaco.

The authors define their geographic scope as what they call the “Chaco Basin,” which is essentially equivalent to what is commonly know in the Chaco literature as the “San Juan Basin.” I think this is a useful change to the terminology, since “San Juan Basin” in the hydrographic sense refers to a much larger area than it is used for in this context, and while some use terms like “San Juan Physiographic Basin” to clarify this, it’s more straightforward to redefine the area and use a new term. “Chaco Basin” is a good term to use because the area more or less corresponds to the drainage basin of the Chaco River, including its tributaries, although it extends a bit beyond to the east and south into the Puerco Valley and Red Mesa Valley respectively. However it’s labeled, this region is roughly bounded by the San Juan River to the north, the Chuska Mountains to the west, the Zuni Mountains to the south, and the Jemez Mountains to the east.

Temporally, the authors restrict their attention in this chapter to the period from AD 700 to 925, unlike some other authors in this volume who also address the preceding Basketmaker III period. This is understandable but in some ways unfortunate, since there was an important Basketmaker III occupation of Chaco Canyon that was likely important in setting the context for Pueblo I developments, just as those developments were important in setting the context for Pueblo II. Confusingly, they use the term “Pueblo I” for sites dating from AD 700 to 875 and “late Pueblo I” for sites dating from AD 875 to 925. As we’ll see below, the distinction between these two periods is important in this region, as population and settlement patterns changed significantly at around AD 875. The specific terms they use still seem odd and liable to cause confusion, however.

Part of the reason the authors argue that the Pueblo I occupation in this region is poorly understood is that the ceramic chronology is different from that of the better-known sites to the north, and using the same types to identify time periods for sites in both regions leads to problems. They carefully define the types they use to identify sites to time period, and also use architectural criteria (which are however difficult to apply to unexcavated sites).

Most of this chapter is a summary of what is known about Pueblo I settlement in each subregion of the Chaco Basin, based in large part on hitherto unpublished fieldwork. As a result, I will structure this post according to the same subregions in the same order and summarize the information on each.

Northern and Northeastern Areas

The heading for this section says “Northwestern” rather than “Northeastern,” but it’s clear from the text that this in error. These areas, north and northeast of the Chaco River but still within the drainage of the San Juan, were sparsely populated throughout the Pueblo period. Windes and Van Dyke note that the Largo and Gobernador canyons, to the northeast of Chaco, may have served as conduits for populations migrating south from the Mesa Verde region into the Chaco Basin in late Pueblo I. A recently discovered village at the confluence of Largo and Blanco Washes included a great kiva and at least 22 habitation sites, with tree-ring dates from the great kiva pointing to construction at about AD 828. This area is roughly due south of the Cedar Hill and Ridges Basin areas of the Animas Valley, considered part of the Eastern Mesa Verde region in this volume, which had extensive but short-lived populations early in Pueblo I. The tree-ring dates from the Largo-Blanco village suggest that it may have been associated with the initial migration out of the Ridges Basin/Durango area in the early 800s rather than the larger migration in the late 800s. The Chaco River may have been another conduit for migrants from the north, as Windes and Van Dyke note that surveys have found a major increase in sites dating to the late 800s along the east side of the Chaco, compared to a virtual absense of sites for earlier in Pueblo I. This will be a recurring pattern in the region.

Chaco Canyon Proper and Environs

The initial survey work of the Chaco Project in the 1970s identified a fairly extensive Pueblo I occupation in and around the canyon, and publications from that time posited a gradual increase in population over the course of Pueblo I leading up to the florescence of Chaco as a regional center in Pueblo II. Based on his more recent work with ceramic classification and dating, however, Windes disputes this account. He argues that the number of sites assigned to Pueblo I in those surveys is vastly inflated, and that for most of the Pueblo I period the Chaco area had a small population which increased dramatically, presumably due largely to immigration, in the late Pueblo I period. In this chapter Windes and Van Dyke (though clearly this part is mostly Windes) summarize the results of Windes’s reevaluations of the Pueblo I occupation in and around the canyon, moving from east to west.

Pueblo Pintado Great House at Sunset

At the east end of Chaco Canyon, the Pueblo Pintado area was apparently unoccupied until about AD 875, when it was colonized by two groups who had markedly different material culture and appear to have come to the canyon from different directions. They formed separate site clusters about 3 km apart, north and west of the later great house of Pueblo Pintado.

The first cluster, located just north of the great house, includes one exceptionally large roomblock more than 50 meters long, accompanied by a trash midden that is also unusually large. Based on the temper of early ceramics in this cluster, the people appear to have come from the Mesa Verde region to the north, presumably as part of the mass exodus following the collapse of the Dolores villages in the late ninth century.

The second cluster, 3 km west of the first one, appears to have also been founded around AD 875 but continued in use well into the Pueblo II period. The ceramics are quite unusual in manufacture for the Chaco area and indicate origins to the south in the Mt. Taylor area. Interestingly, the roomblocks in this cluster were aligned along the road connecting the Pueblo Pintado community to the core area of Chaco Canyon, implying that this road may date to the late Pueblo I period.

Moving west, the next major cluster of Pueblo I sites is what is known as the Chaco East community, which also featured a later great house. This area also appears to have been unoccupied until about AD 875, when it was colonized by a group occupying small residential sites, possibly only seasonally. In the 900s the community grew considerably, and initial construction of the great house may date to this period, although it’s impossible to tell for sure without excavation.

Third-Story Walls with Type I Masonry at Una Vida

Fajada Gap, at the eastern end of the main concentration of sites in Chaco during Pueblo II, is one of the areas where early surveys indicated a dense Pueblo I occupation which Windes disputes based on current understandings of the ceramic chronology. In fact, while there was unquestionably a small occupation of the area throughout Pueblo I involving scattered hamlets, this appears to be yet another part of the canyon where there was an influx of people in the late 800s who established the basis for the community that developed subsequently. There are two great houses in this community, Una Vida and Kin Nahasbas, both of which were constructed beginning in the late ninth century.

The largest Pueblo I (pre-875) settlement in the Chaco area is actually outside the canyon, along the South Fork of the Fajada Wash. This community contained 26 sites in an arc along the west side of the South Fork; no contemporary sites are present on the east side. The community is loosely clustered around a complex of four roomblocks which were connected by a short road to a great kiva, and it likely included about 230 people overall. Its main occupation was around AD 800, making it contemporary with the earlier villages in the Mesa Verde region, but the layout of the community is more like later villages such as those at Cedar Hill and in the Largo drainage. (The description of the community in this chapter is very confusing and it’s hard to tell in what respects it’s being described as similar to or different from villages in other regions.)

Many of the potsherds from the South Fork community were tempered with chalcedonic sandstone, which is typical of sites to the south near the modern community of Thoreau. There is also an unusually high abundance of yellow-spotted chert among the chipped stone assemblage, again indicating connections to the south. This type of chert occurs in the Zuni Mountains near Thoreau and is common in sites in that area.

Although this was the largest Pueblo I community in the Chaco area, it appears to have been very short-lived, with little trash accumulation. This suggests that the Pueblo I period was a dynamic time of extensive population movements in this area just as it was in the better-understood areas to the north. The subsequent Pueblo II occupation of the South Fork was much more extensive than the Pueblo I occupation and quite different, with sites dispersed up and down the valley rather than clustered in one area. A similar though somewhat smaller cluster of sites dating to the Pueblo I period was also present in the upper reaches of Kin Klizhin Wash to the west of Fajada Wash.

Old Bonito

Returning to the main canyon, there were a few scattered Pueblo I hamlets between Fajada Gap and South Gap, but the occupation doesn’t seem to have been extensive. Even in South Gap itself, an area of considerable density during Pueblo II and the location of the cluster of great houses known as “Downtown Chaco,” Pueblo I occupation was sparse, with a few scattered sites in the gap. Apparently the only Pueblo I site known in this part of the canyon proper is Pueblo Bonito, where the earliest construction of the great house, known as “Old Bonito,” dates to the mid-800s (or possibly even earlier) and there is also an earlier pit structure excavated by Neil Judd in the 1920s. Judd thought the pit structure reflected an earlier occupation unrelated to the great house, but with improved dating showing that the great house was begun earlier than had been thought the idea of continuity is beginning to seem more likely.

There is no evidence for Pueblo I occupation between South Gap and the mouth of the canyon, possibly on account of flooding creating an intermittent lake on the canyon floor. At the mouth of the canyon itself, the Peñasco Blanco great house, begun in the late 800s, sits atop West Mesa, and right next to it is the important Basketmaker III village of 29SJ423. The period between these two important occupations, however, appears to have involved only minor settlement, although there are a few scattered Pueblo I sites. Just west of the mouth of the canyon, however, is Padilla Wash, which had a substantial Pueblo I occupation (possibly even more extensive than current records indicate, since many Pueblo I sites may have been misclassified as Basketmaker III in earlier surveys), another example of the main centers of Pueblo I population in the Chaco core being outside the canyon proper. Windes and Van Dyke note that Peñasco Blanco may have been an important focal point for migration into the canyon from the west and north during late Pueblo I, and that it was likely more important than Pueblo Bonito at this time.

The Chaco River

As noted above, the Chaco River (formed by the confluence of the Chaco and Escavada Washes at the mouth of Chaco Canyon) was likely one of the main conduits for migrants from the north, but it was much more than that. Pueblo I communities existed all along the Chaco and its tributaries, and some of these communities included early great houses that would have been influential in the development of the great house phenomenon that found its greatest expression in Chaco Canyon in the eleventh century. Windes and Van Dyke discuss a number of these communities, based on field research by Windes to reevaluate areas identified by early surveys as Chacoan outlier communities and to look for evidence of Pueblo I settlement and early great houses.

Just west of Padilla Wash is Kin Klizhin Wash, which was the site of extensive Pueblo II occupation but only has a few Pueblo I sites aside from the cluster at its upper reaches mentioned above. There is a late Pueblo I great kiva known as Casa Patricio in the upper part of the drainage, accompanied by a number of late Pueblo I residential sites; it’s not clear from the writeup here what relationship this site cluster has to the earlier Pueblo I cluster.

Just downstream from the mouth of Kin Klizhin Wash is the very important early site known as Casa del Rio. While this was initially labeled a large Chacoan great house, reexamination indicated that it is actually a composite of two building stages, both relatively early, with much of the bulk of the structure provided by a Pueblo I roomblock measuring 112 meters in length, with a later masonry great house built over the central portion beginning in the late ninth century. The early roomblock is by far the largest in the Chaco Canyon region, more than twice the length of the earliest construction stage at Pueblo Bonito, and it is estimated to have housed about 16 households or 88 residents. Windes and Van Dyke describe it as “reminiscent of those north of the San Juan River,” although again it is not clear what specific characteristics this refers to. A large number of food preparation tools were found in the area, although other residential sites are scarce. This was clearly an important site during the Pueblo I period which may have played a key role in attracting migrants to the area.

Looking North from Kin Bineola

One of the most important tributary drainages of the Chaco River is Kim-me-ni-oli Wash, which extends from the Dutton Plateau north past the current site of Crownpoint. The drainage of this wash includes several great houses and extensive Pueblo settlement, and it likely served as an important conduit between Chaco Canyon and areas to the south and southwest. The extent of Pueblo I occupation, however, seems to be unclear. Windes and Van Dyke mention large circular structures near the Bee Burrow great house that resemble Pueblo I great kivas, as well as small Pueblo I roomblocks in the same general area. The area around the Kin Ya’a great house at the upper end of the drainage appears to not have any Pueblo I occupation based on existing survey data, although there is a large Basketmaker III-Pueblo I site just west of Crownpoint and one arc-shaped roomblock near Kin Ya’a recorded as dating to Basketmaker III looks a lot more like a Pueblo I site. At Kin Bineola, site of a major great house dating to the early 900s or possibly slightlier earlier, there is a very small Pueblo I occupation that increased substantially after AD 875 as in many other parts of the region.

At the mouth of the Kim-me-ni-oli Wash near the current Lake Valley Mission there is a small cluster of Pueblo I sites “architecturally identical” to the South Fork cluster, with very sparse refuse indicating a very short occupation. A later occupation in the late 800s was more substantial, with three masonry roomblocks “sometimes portrayed as small great houses” and “enormous amounts of refuse” that Windes and Van Dyke describe as “excessive for normal domestic activities.”

Further down the Chaco drainage, the Willow Canyon area is unusual in showing evidence of both middle and late Pueblo I occupation in close proximity. The middle Pueblo I community consists of eight sites that show the typical “scattered hamlet” settlement pattern, while the eleven late Pueblo I sites are tightly clustered and associated with a large amount of refuse, leading the authors to interpret this as “a large group” that immigrated into the valley together. These sites show unusual amounts of Type I masonry, associated with later great house construction, although the authors declare that there is no “obvious” great house. It’s not clear what definition of “great house” they are using here, as one site in particular (known as the “House of the Weaver”) shows not only Type I masonry but a prominent mesa-top location with a broad view of the surrounding area, another common characteristic of later great houses. Another community south of Willow Canyon near the later Whirlwind great house also shows a similar pattern but has less information available. The Great Bend area, where the Chaco River turns from flowing west to flowing north toward the San Juan, also shows this pattern. The possible use of the river as a corridor for populations migrating from the north after the collapse of the Dolores villages makes this potentially an important area for understanding regional prehistory.

Chuska Mountains and Chaco River from Peñasco Blanco

The eastern flanks of the Chuska Mountains, which parallel the north-flowing segment of the Chaco River and form the western side of its drainage basin, are also important for understanding Pueblo I settlement but are poorly known. The general pattern seems to be the same as elsewhere in the Chaco Basin, with a scattered occupation in early and middle Pueblo I that sees a huge increase, presumably from immigration, in late Pueblo I after AD 875, but due to depositional factors it’s likely that the earlier Pueblo I occupation has been underestimated. A few sites dating to this period have been excavated through salvage projects. Late Pueblo I sites are more common and seem to provide more evidence for the use of the river as a corridor from the north. The largest concentrations are in the Skunk Springs and Newcomb areas, both of which would become major Chacoan outlier communities in Pueblo II. At Newcomb, at least, there seems to be some evidence of a preexisting Pueblo I occupation. It’s not clear if there is any similar evidence at Skunk Springs, where the earliest stage of construction on the great house seems to date to late Pueblo I. Given the importance of Chuskanimports to Chaco at its peak, more research on the background of these communities would be helpful in understanding Chaco’s origins.

The Red Mesa Valley

The Red Mesa Valley is the area between the Dutton Plateau on the north and the Zuni Mountains on the south. It is topographically rather than hydrologically defined, and straddles the Continental Divide, with the western part drained by the Rio Puerco of the West and the eastern part drained by the Rio San Jose. This means it falls outside of the “Chaco Basin” as hydrologically defined, of course, but its culture history means that it makes sense to include it with areas to the north for purposes of this chapter. This valley was presumably an important travel corridor prehistorically, as it certainly was historically with the railroad and Route 66 running through it and remains today with Interstate 40.

Casamero Pueblo

This area has been the main focus of Van Dyke’s research, and it is clear that she rather than Windes is responsible for most of this section of the chapter. The same issues of ceramic identification as in the Chaco Basin make understanding the Pueblo I sequence here difficult, but the same basic pattern appears to apply as further north. Early in Pueblo I there was a small, scattered occupation, exemplified by a site on the mesa above the later Chacoan outlier community of Casamero. This site consists of at least two arcs of surface rooms fronted by five to seven pit structures, and resembles White Mound Village further west along the Puerco, which was excavated by Harold Gladwin in the 1940s and dates to the late 700s and early 800s. Another site like this from the same period was excavated near Manuelito during the construction of I-40 in 1961.

This sparse population expanded immensely in late Pueblo, when many of the later Chacoan great house communities were founded. Some of the earliest great house construction in the region took place in these communities, which Van Dyke has elsewhere used to argue that great houses were not initially associated particularly with Chaco Canyon specifically. The huge increase in population at this time seems to indicate immigration, but this chapter doesn’t address the issue of where the people in this area might have come from. Given the similarities to the communities to the north in the Chaco Basin, that seems like an obvious point of origin (with earlier origins probably further north in the Mesa Verde region), but developments to the south are poorly understood and can’t be ruled out as important factors. As noted above, some of the immigrants to Chaco Canyon and its surrounding area appear to have come from the south rather than the north, and southern origins would presumably be even more likely for the Red Mesa Valley populations given their location. The fact that the influx here appears to happen at the same time as the northern one is an interesting complication, however.

The Eastern Chaco Basin

This area, stretching from the area south of Chaco Canyon across the Continental Divide to the Rio Puerco Valley of the East, shows very little evidence for Pueblo I occupation. Today this is a very sparsely populated area used mainly for cattle ranching, primarily on private land, so there has been little archaeological survey, but what survey has been done shows very little prehistoric occupation at all. Only two exceptions are noted by Windes and Van Dyke. One is a recently discovered Pueblo I community southeast of Mt. Taylor, about which little is known. Detailed information from the survey that identified this community is apparently not going to be released. It’s not clear from the brief writeup if this has anything to do with the fact that the survey was for proposed uranium mining.

The other exception is the Puerco Valley of the East, around the later Chacoan outlier of Guadalupe. Here, survey by Eastern New Mexico University in the 1970s identified a “modest but scattered” Pueblo I occupation, which increased substantially in late Pueblo I and Pueblo II, culminating in the Guadalupe community with its apparently close connections to Chaco Canyon. Windes and Van Dyke note that the Puerco may have served as an important conduit connecting the Chaco Basin to areas further east, although it remains poorly understood. The eastern associations of Chaco are poorly understood in general, and this appears to be the case as much for Pueblo I as for Pueblo II.

Storm in the Distance through Fajada Gap

After going through the detailed geographical summaries, the authors briefly address some region-wide issues important for understanding the patterns they describe. They acknowledge environmental factors as probably important in understanding population shifts, pointing in particular to an apparent “spike” in rainfall in the immediate area of Chaco Canyon between AD 885 and 905 that might have served as a “pull” factor bringing people in from other areas. Conditions in the Chuskas and Red Mesa Valley appear to have been generally unfavorable during this period in which they, too, saw significant immigration, so clearly rainfall totals weren’t the only factor.

They also discuss violence, noting that there is very little evidence for it in this region, particularly in the central Chaco Basin, during Pueblo I, especially compared to areas further north where burned structures are common. There are more burned structures in the Chuskas and near Mount Taylor, on the edges of this region, however, and it is possible that the lack of them in the central basin relates more to the lack of construction wood than to any lack of violence. The authors suggest that, given the known evidence for strife and community abandonment in the Mesa Verde region, one attraction of the Chaco Basin might have been its relative emptiness, which may have drawn people into this much harsher and less fertile region. There’s a general tendency for settlement to cluster around drainages and particularly at confluences of drainages, likely because these locations offered the best agricultural potential in a very dry area even by Southwestern standards. Regardless of what it was that initially drew people into this area, it’s becoming increasingly clear that this influx of population was a key factor in the later rise of Chaco.

Peñasco Blanco Framing Huerfano Mesa

The authors also discuss visibility and sacred geography, which has been a key concern of Van Dyke’s in her previous work. Many of the prominent community buildings in late Pueblo I sites in this region, whether or not they can be considered “great houses,” are situated in locations where important regional landmarks can easily be seen. This indicates that the concern with visibility associated with later Chacoan great houses likely had its roots in this period.

Finally, the authors summarize community settlement patterns in the region. One interesting pattern they note is that in late Pueblo I communities great houses and great kivas don’t tend to occur together, with great houses being more common in the Chaco Basin and great kivas in the Red Mesa Valley. This suggests that two different community integration systems may have been in place in the region during this time. The great house pattern at more northerly sites is interesting in the context of the “proto-great-houses” apparently present at some Dolores area communities further north, especially McPhee Village, and it’s quite likely that there is a direct connection between the two. Great kivas are also common further south, and while they were present at some Mesa Verde Pueblo I sites they weren’t very common. This suggests that at least some of the Red Mesa Valley late Pueblo I communities were in fact settled by immigrants from the south rather than from the Chaco Basin. Some of the earliest communities showing both features were in Chaco Canyon, and it may well be that one factor in the rise of Chaco was the ability of emerging elites there to combine the two traditions into a new social and ideological system, one that would spread far and wide, remaking the course of Southwestern prehistory.

Today is the winter solstice, which means it’s also the sixth anniversary of this blog. On these anniversaries I like to write about archaeoastronomy, which is a very interesting topic and an important one for understanding Chaco and Southwestern prehistory in general. Last year I wrote about some research indicating that in the Rio Grande valley, an area generally thought to be outside the Chaco system but that was certainly occupied at the same time as Chaco, there was a long and very consistent tradition of orienting pit structures to the east-southeast, which is the direction of winter solstice sunrise. The winter solstice is very important in the cosmology and rituals of the modern Pueblos, so it makes a lot of sense that at least some Pueblo groups would orient their dwellings based on it.

As I noted at the time, this orientation is very different from that in the San Juan region to the west, including Chaco and Mesa Verde. In this area there is an equally long tradition of orienting pit structures to either due south or south-southeast. I’ve long wondered why this might be, and an article I read recently discusses the issue and proposes some interesting potential answers.

The article is by Kim Malville and Andrew Munro and was published in the journal Archaeoastronomy in 2010 as part of a special issue on archaeoastronomy in the Southwest. Malville is an astronomer who has done a lot of research on archaeoastronomy in the Southwest and identified many potential astronomical alignments, but this article is actually largely about debunking many of the alleged alignments claimed by others, particularly Anna Sofaer and her Solstice Project. Sofaer, an artist who turned her attention to archaeoastronomy after discovering the “Sun Dagger” effect involving a spiral petroglyph on Fajada Butte that on the summer solstice appears (or appeared) to be bisected by a “dagger” of light coming through a slit between large boulders in front of it. Sofaer went on to organize surveys of the major great house sites in Chaco Canyon to identify any celestial alignments in the orientation of their walls, and her team found that virtually all of them did show alignments to the positions of the sun or moon on solstices, equinoxes, or lunar standstills.

Light Snowfall on Fajada Butte

Sofaer and her collaborators went on to publish these findings widely, and to make a well-known documentary that has often been shown on television and inspired a lot of interest in Chaco. As Malville and Munro show in this paper, however, the evidence for these alignments is very thin. There is little to no justification in Pueblo ethnography for the idea of celestial building alignments, and the alignments themselves are identified with a substantial margin for error that makes spurious positive identifications likely, especially when so many potential alignments are tested for. Particularly concerning is how many of the alignments are to the minor lunar standstill, which is not a very impressive or noticeable event. (The major lunar standstill is a different story, and there is strong evidence at Chimney Rock in Colorado that the Chacoans were familiar with it and considered it important.) Malville and Munro also argue that the fact that most of the alignments are based on the rear walls of sites is also questionable, since there is no evidence that rear wall alignments were or are important culturally to Puebloans.

Instead, they argue that the alignments of rear walls are epiphenomenal, and that they mostly result from the more solidly established concern with the orientation of the front of a site. The bulk of the article is devoting to tracing these frontal orientations across time and space, with a primary focus on Chaco itself and on the earlier Pueblo I villages in the area of Dolores, Colorado that are often seen as being partly ancestral to the Chaco system.

As I noted above, there are two main orientations that persist through time in the San Juan region. One is to due south, and the other is to the south-southeast (SSE). With pit structures these axes are typically defined by a straight line of sipapu (if present), hearth, deflector, and vent shaft. There is often also a measure of bilateral symmetry between features on either side of this line, such as support posts. When there are surface rooms behind a pit structure, they often (but not always) conform to the same alignment, and when the back of a row of surface rooms is straight, it is typically perpendicular to the main orientation. Malville and Munro argue that these perpendicular back walls on many Chacoan great houses, which Sofaer has identified as having alignments to various astronomical phenomena, are really subsidiary effects of the main emphasis on frontal orientation.

The authors start their survey of orientations with the Basketmaker III pithouse village of Shabik’eschee at Chaco. Of 15 pithouses for which they could find adequate information on orientation, 11 faced SSE with an average azimuth of 153.7 degrees and 4 faced south with an average azimuth of 185 degrees. Strikingly, none of the pithouses showed any other orientation.

The north-south orientation isn’t difficult to understand, and Malville and Munro attribute it to use of the night sky for navigation (which would have been easy enough at this time even though there wasn’t actually a north star), and they also mention the widespread presence of Pueblo traditions mentioning origins in the north. While the exact reasons for adoption of this orientation may not be clear, its consistency isn’t unexpected since it’s pretty obvious and easy to replicate.

The SSE orientation, on the other hand, is a different matter. Note that at Shabik’eschee this was much more common than the southern orientation, from which it is offset by about 20 to 30 degrees in individual cases. There is more variation in this orientation than with the southern one (standard deviation of 7.7 degrees versus 2.4), but it’s sufficiently consistent and common that it seems like there must be some specific reason for it. Unlike the southern orientation, however, it’s not at all clear what that might be. Malville and Munro, sticking to their interpretation of orientations as references to places of origin, suggest that in the case of Shabik’eschee it might reflect the fact that some people might have migrated to Chaco from an area that was more to the north-northwest than due north, which seems implausible to me but then I don’t have a better explanation myself.

McPhee Reservoir, Dolores, Colorado

In any case, this pattern continues through time. The next set of orientations Malville and Munro look at are those of the pit structures at the Pueblo I Dolores villages. What they find is that SSE orientations are dominant here too, even more so than at Shabik’eschee. In fact, all of the pit structures they looked at had SSE orientations except those at Grass Mesa Village, which mostly faced faced south (although even here there were a few SSE orientations). This is in keeping with other evidence for differences in architecture among different villages at Dolores; Grass Mesa is known for having long, straight room blocks, as opposed to the smaller and often crescent-shaped roomblocks at McPhee Village, which with it is most often compared.

The Duckfoot site, to the west of the Dolores villages but contemporaneous with them, also had a SSE orientation. Further west, however, southern orientations become more common, including at the important village sites of Yellow Jacket and Alkali Ridge, plus some of the earlier Basketmaker II sites on Cedar Mesa in Utah.

There was one more orientation used during the Pueblo I period in the Northern San Juan region, however. At Sacred Ridge, in Ridges Basin near modern Durango, Colorado, the average azimuth of the pit structures is 120 degrees, the same east-southeast orientation corresponding to winter solstice sunrise so common in the Rio Grande. Malville and Munro remark on the similarity to the Rio Grande pattern and consider it “puzzling,” positing some potential ways that it could have come about. They argue, however, that wherever this pattern came from it didn’t last in the north, and they point to the extremely violent end to the occupation of Sacred Ridge as the end of this orientation tradition in the San Juan region (although this may not be strictly true, as discussed below).

From here Malville and Munro turn back to Chaco. Specifically, they look at the great houses at Chaco during its heyday from about AD 850 to 1150. Rather than pit structures, they focus on roomblocks, and they interpret the orientation of a roomblock to be the perpendicular to its long axis (in the case of rectangular roomblocks) or the perpendicular to the ends of the crescent of roomblocks with that shape. They find that most of the great houses have a SSE orientation, in keeping with the general trend throughout the region, as do the three northern outlier great houses of Chimney Rock, Salmon, and Aztec. Since this orientation is very close to the perpendicular of the minor lunar standstill moonrise alignment that Sofaer has proposed for many of these buildings, Malville and Munro argue that this widespread orientation explains the pattern much better than the lunar alignment. Pueblo Alto and Tsin Kletzin have north-south orientations, which is unsurprising since they lie on a north-south line with each other.

A few of the great houses have a more complicated situation. Peñasco Blanco appears to face east-southeast at an azimuth of approximately 115 degrees. This is intriguingly close to the Rio Grande/Sacred Ridge winter solstice orientation, which Malville and Munro do note. Although the unexcavated nature of the site makes it hard to tell for sure, it is possible that this is in fact an example of this orientation surviving much later in the San Juan region than the destruction of Sacred Ridge, although what, if any, connection there might be between the two sites is unclear.

Pueblo Bonito from Above

And then there’s Pueblo Bonito. While the very precise north-south and east-west cardinal alignments of some of the key walls at this site are well known, it has also long been noted that there is evidence for different alignments and change over time here. Malville and Munro interpret the early crescent shape of the building as having a SSE orientation, and like many others they relate it to the similar size, shape, and orientation of McPhee Pueblo at McPhee Village. They then describe multiple stages of drift away from this orientation toward the cardinal orientation. There is surely something to this interpretation, but a careful look at the stages of construction of the site shows that the picture is probably more complicated. The very first construction at Bonito appears to have been straight and oriented to the south, and to have been incorporated later into the SSE-facing crescent. Subsequent building stages show evidence of both orientations having been present throughout the history of the building.

The complicated situation at Pueblo Bonito provides a convenient segue to the key issue here: what was driving this long-term but consistent variation? Why were two different orientations for buildings present in close proximity for hundreds of years, even as populations moved long distances and adjusted their cultures in profound ways? Malville and Munro suggest that these orientations may reflect longstanding cultural and ethnic diversity in the prehistoric Southwest. Given how long-lived and consistent these patterns are, they propose that they were related to deep-seated cultural identities. This is an intriguing idea that may allow tracking of specific cultural groups across the Southwest over centuries. It also provides another piece of evidence that Chaco Canyon was a multicultural community, and implies that even Pueblo Bonito itself contained groups with diverse backgrounds.

The picture is probably even more complicated than Malville and Munro suggest. They tend to implicitly assume that the orientations of pit structures are the same as those of the room blocks with which they are associated, but at least at Chaco this is not necessary true, particularly for small-house sites, which they also don’t address at all in this study. There are many examples of small houses where the room blocks are oriented to the east but the pit structures are oriented to the south (and possibly also SSE, although I haven’t checked this). This eastern orientation may reflect connections to the south, which have gotten a lot less attention in the literature than connections to the north although they appear to have been pretty important in the origins of Chaco.

In any case, I think this is fascinating stuff. It may not be archaeoastronomy per se, but it seems like a fitting way to mark the solstice.Malville JM, & Munro AM (2010). Cultural Identity, Continuity, and Astronomy in Chaco Canyon Archaeoastronomy, 23, 62-81

Happy Fourth of July, everyone. The Fourth is actually a pretty important date for the study of Chaco, but in a roundabout (and somewhat controversial) way. It all has to do with a very famous pictograph panel below Peñasco Blanco at the west end of the canyon. While the interpretation of this panel is a matter of considerable debate, one way it’s been seen is as a record of an astronomical event that is known to have occurred during the height of Chaco’s power and influence: the supernova of 1054, which formed the Crab Nebula.

We know from several Chinese reports that the “guest star” resulting from the supernova first appeared on July 4, 1054 and continued to be visible day and night for almost two years. There are a few Japanese records of the supernova as well, along with one report from the Arab world. No clear-cut and unambiguous accounts are known from Europe or elsewhere in the world, although a few rock art panels in the Southwest have been proposed as representing the event. The most famous of these is the one at Chaco, which is often referred to as the “Supernova Pictograph” (even by the park itself in a sign at the site). It consists of three symbols painted onto the rock face in red: a hand, a crescent, and a starburst-like shape. It’s the starburst that has been interpreted as representing the supernova itself, of course, and the crescent has been seen as representing the crescent moon. On the morning of July 5, the moon, which was a crescent at the time, would have appeared in roughly the same relationship to the supernova, as seen from the pictograph site, as the relationship between the two symbols on the panel. Furthermore, the handprint points in the direction one would have looked to see this at at the time. The combination of the three symbols together, plus the fact that this would have happened at a time of considerable activity in the canyon, has led some to suggest that this pictograph panel was created to commemorate this historic event. The specific location may have been an established sun-watching position, from which the new star was seen unexpectedly and recorded.

Sign at the "Supernova Pictograph"

It all sounds fairly plausible as it goes, but there are some problems with this theory. Probably the biggest problem is that the specific set of symbols on the panel is known from ethnographic evidence to have been used by the Zunis to mark generic sunwatching sites, with the crescent representing the moon, the starburst representing the sun, and the hand marking the location as sacred. Now, it’s certainly possible that these symbols came to be associated with this activity as a result of the observation of the supernova at this site, but as far as I know there’s no reference to the supernova in ethnographic descriptions of astronomical observation at Zuni or any of the other modern Pueblos, so this is a pretty tenuous claim.

Furthermore, while the 1054 supernova would certainly have been noticeable at Chaco, there was an earlier supernova in 1006 (also recorded by the Chinese, and possibly by the Hohokam in southern Arizona) that was much brighter, and it’s not clear why the Chacoans wouldn’t have recorded that one too. It took place before the Chaco system really got going on a regional scale, but there was plenty of activity in the canyon during the 900s, so people there would presumably have seen it. It’s possible that it was recorded too, at some other site that hasn’t been found or that has disappeared in the thousand years that have elapsed since the event (note that the existing Supernova Pictograph has only survived because it was under a protective overhang), but again, there’s not any evidence for this. The Chacoans are definitely known to have kept careful track of regular patterns in the skies, such as the solstices and the lunar standstills, so they surely would have seen unusual events such as supernovae, but it’s not clear how they would have reacted to them or how inclined they would have been to record them.

View Looking East from "Supernova Petroglyph"

So it’s not really clear how to interpret the Chaco pictograph. I think the balance of evidence at this point leans slightly against it being a representation of the supernova, but I could be talked out of that position if some additional evidence for the supernova theory can be found.

Others, however, have proposed even more extreme theories based on the 1054 supernova. Among the more noteworthy of these is a proposal by Timothy Pauketat and Thomas Emerson, in a 2008 article in the Cambridge Archaeological Journal, that the rather sudden florescence of the Cahokia site in Illinois around AD 1050 may have had something to do with the supernova. The theory they present is interesting, but hard to effectively support. For one thing, dating methods in the Midwest are much less precise than in the Southwest, so pinning down any event to the year is usually not possible. There is certainly a suggestive correspondence between the sudden rise of Cahokia and the supernova, however, and this is supported by the apparent use of stellar imagery and symbolism at Cahokia and the importance of the stars to later cultures in the area, so there may well be something to this.

Opening at Casa Rinconada That Channels Sunbeam at Sunrise on Summer Solstice

I’m a bit troubled, however, by the reliance of Pauketat and Emerson on evidence from Chaco and the way they interpret it. For one thing, they say that the Supernova Pictograph is “above” Peñasco Blanco, when it’s actually below it, and not visible from the great house itself. More importantly, they say of the effect of the supernova:

Some believe that this particular cosmic event, which left behind the Crab Nebula, was commemorated in architecture and iconography at the time or in subsequent years. The most compelling evidence for this comes not from the Cahokia region but from the American Southwest, where a tree-cutting date places the construction of the largest and most isolated ceremonial building in Chaco Canyon, Casa Rinconada (noted for its many astronomical alignments) to AD
1054.

Now, it’s true that there is a single tree-ring cutting date from Casa Rinconada that dates to 1054. This is, however, the only tree-ring date for the site, so while it’s plausible that it dates the construction of the site this definitely cannot be stated as definitively as Pauketat and Emerson state it here. There is no specific provenience information available for this beam, so there’s no way to tell how it was used and whether it can plausibly be said to date to the initial construction of the site. The general architecture of Casa Rinconada is consistent with a construction date in the 1050s, but without more specific information tying it to a specific year on the basis of one unprovenienced beam is unwarranted.

Furthermore, even if Rinconada was built in 1054, that doesn’t establish that it was built because of the supernova. There was extensive construction in the canyon throughout the mid-1000s, associated with Chaco’s apparent rise to regional dominance, and this began well before 1054. The major expansion of Pueblo Bonito began by the 1040s at the latest, and various other construction projects at other sites in the canyon dates to this general period. Rinconada could easily have been part of this general process without any specific relationship to the supernova. Indeed, there’s nothing about Rinconada that seems to refer to the supernova, despite the various astronomical alignments (some of them controversial as well, it should be noted) identified there.

None of this means that the supernova didn’t have an important role at Cahokia, of course, and it doesn’t even rule out an important role at Chaco itself. It does mean, however, that developments at Chaco shouldn’t really be used as evidence for developments at Cahokia, even though the two sites are contemporaneous and Chaco can be dated much more precisely. Cahokia may well have risen as a result of the 1054 supernova, but neither the Supernova Petroglyph at Chaco nor the one tree-ring date at Casa Rinconada provides evidence that it did.Pauketat, T., & Emerson, T. (2008). Star Performances and Cosmic Clutter Cambridge Archaeological Journal, 18 (1), 78-85 DOI: 10.1017/S0959774308000085

In a recent post, I noted the limited distribution of macaw remains within Pueblo Bonito. While this site has a much higher number of macaws than any other Chacoan site, and more than almost every other site in the prehistoric Southwest, within the site macaw remains were highly concentrated. All macaws were found in the eastern half of the site, and most were in the eastern part of “Old Bonito” at the northern end of the overall site, particularly in Room 38, which had twelve. This suggests to me that macaws were closely associated with whatever social group lived in or used that part of Pueblo Bonito.

It’s hard to say what that social group was, but it’s possible that the burials in a complex of four rooms in the northern part of Old Bonito were associated with it. Associating these burials with the eastern rooms in Old Bonito is perhaps a bit of a stretch, since the burial rooms are actually in the western half of the Old Bonito arc, but they’re just barely on the west side, and there is a separate set of burial rooms at the far western end of Old Bonito that could be plausibly associated with whatever social group lived in or used those rooms. There is no equivalent set of burial rooms in the eastern part of the arc, although there are a few isolated burials of infants and fetuses. (Two of the infant burials, in Rooms 306 and 309, were associated with macaws.) The eastern end of Old Bonito was covered over by later construction and is poorly known, but there is no evidence that it ever held a mortuary complex comparable to the one at the western end. Given the circumstances, I think it’s plausible that the northern burial complex was associated with the group (or one of the groups) associated with the eastern part of Pueblo Bonito, perhaps in addition to the group associated with the immediately adjacent room suite at the west end of the northern part of Old Bonito, if this was indeed a different group.

Western Burial Rooms in Old Bonito

Analysis of the Pueblo Bonito burials by Nancy Akins for the Chaco Project found that, judging from cranial attributes, the northern and western burial groups were distinct from each other but internally homogeneous. This suggests that they probably represented kin-based social units, and that the site consisted of at least two of these units, perhaps occupying or using different areas. Akins couldn’t find a very large sample of burials from other sites in the canyon for comparison, but she was able to compare burials from three small sites in the canyon. One of these, Bc 59, is across from Bonito on the south side of the canyon near Casa Rinconada, while the other two, 29SJ299 and 29SJ1360, are in Fajada Gap, a few miles east and the location of a substantial community of small houses and two great houses (Una Vida and Kin Nahasbas) in close proximity to Fajada Butte.

While the two burial populations in Pueblo Bonito weren’t particularly similar to each other, they more closely resembled the small site samples. Specifically, the western burial population was similar to the one from Bc 59, while the northern burial group was more similar to the Fajada Gap group. Importantly, the two Bonito groups were both more similar to these small-house populations than they were to each other. This suggests that kinship connections among different sites in the canyon were complicated and didn’t break down on straightforward great house v. small house lines.

Bc 59 from Casa Rinconada

What does all this have to do with macaws? Well, there is only one small house site at Chaco (as far as I know) that has produced macaw remains, and that site is… 29SJ1360, one of the sites with burials that patterned with the northern burial group at Bonito! As reported by Peter McKenna in his report on this site, which was excavated by the Chaco Project, a few macaw bones were found in the fill from one of the pit structures. While there were only a few bones found, they were all unique, suggesting the presence of only one macaw, and from various parts of the body, suggesting that the whole macaw was present. This fill was only casually screened for artifacts and was later used to backfill the pit structure, so the rest of the macaw is probably still there. This site also had an unusual architectural feature, a small bin attached to the outside of one of the roomblocks, that according to McKenna looked “remarkably like a parrot bin.” One important feature that appears to have led to this conclusion was the presence of an adobe “plug” in the north wall, presumably reminiscent of the stone plugs used with “cage stones” at macaw pens at Casas Grandes, where there is substantial evidence for the keeping and breeding of macaws a few hundred years later.

This is all pretty tentative, of course. Very few sites at Chaco have been excavated, so we have very little sense of the overall distribution of rare finds such as macaw remains. Still, two separate lines of evidence (biological relationship and association with macaws) seem to point to a strong connection between the northern/eastern part of Pueblo Bonito and at least some sites in the Fajada Gap community, which is not particularly close to Bonito. Given the rarity of macaws, especially, this seems significant.

The Basketmaker III period (ca. AD 500 to 750) is a very important time for understanding the prehistoric Southwest. Maize agriculture had been introduced earlier, although exactly how early is still a matter of debate, and it was definitely well-established by the immediately preceding Basketmaker II period, but Basketmaker III saw the introduction of beans, pottery, and the bow and arrow, all of which led to major changes in the lifestyles of local agriculturists. Residence was in pithouses, which are clearly ancestral in form (and probably in function) to the “kivas” of later sites, and while these are usually found isolated or in very small groups, there are a few known examples of large “villages” containing dozens of pithouses. The processes that led to the formation of these sites, as well as their relationships to the more common isolated sites, are very poorly understood, but it seems pretty clear that residential aggregation in certain locations during this period set the stage for the later formation of large villages during the succeeding Pueblo I period and afterward.

Two of the largest and best-known Basketmaker III villages are in Chaco Canyon. The better-known of these, by far, is called Shabik’eschee Village, and it is located on the lowest terrace of a finger of Chacra Mesa at the east end of the current Chaco Culture National Historical Park. Shabik’eschee was excavated by Frank H. H. Roberts in the 1920s as part of the Smithsonian/National Geographic project led by Neil Judd. The main focus of the project was the excavation of Pueblo Bonito, but Judd had other members of the team, including Roberts, excavate several other sites in and around the canyon as well. Roberts published his results in 1929, and this publication has been enormously influential in shaping subsequent interpretations of Basketmaker III villages and the period as a whole.

Looking South from Peñasco Blanco toward 29SJ423

The Chaco Project in the 1970s did some additional work at Shabik’eschee, as well as at the other Basketmaker Village in the canyon. This site, known as 29SJ423, is just south of Peñasco Blanco at the far west end of the canyon, near the confluence of the Chaco and Escavada Washes. It is situated in a similar location to Shabik’eschee, on a lower terrace of West Mesa (but above Peñasco Blanco, which is on the lowest terrace). Tom Windes excavated a small portion of 29SJ423 in 1975, but he and other Chaco Project personnel soon came to the conclusion that additional excavation there would not be worth the considerable effort involved. The collections from this excavation are important, however, since they were acquired using more careful, modern methods than Roberts’s. Similarly, a very small amount of additional excavation at Shabik’eschee in 1973 has provided important supplemental information with which to evaluate Roberts’s interpretations.

Windes and Chip Wills published an article in 1989 looking back at Roberts’s interpretations at Shabik’eschee in the light of the additional knowledge gained by the Chaco Project excavations. They concluded that some of Roberts’s ideas, such as his proposal that the site had two discrete periods of occupation separated by a hiatus during which it was abandoned, are likely untenable, and they also concluded that the site was considerably larger than Roberts thought. They agreed with Roberts that some of the pithouses had been abandoned and their materials were used in subsequent construction, but they saw this as more of an ongoing process related to the short use-life of pithouses and the demands of demographic processes rather than a discrete series of two occupations. They also saw more spatial patterning in the layout of pithouses within the site than Roberts did, suggesting that the pithouses grouped into what might be family residence units, although they were quite tentative in this finding and did not use these groups as units for any subsequent analysis.

Pinyon Trees, Pipe Spring National Monument

Wills and Windes also posited a novel interpretation for the site as a whole. Rather than seeing it as a permanent agricultural village, they saw it as a site of occasional gatherings of more mobile families practicing a “mixed” subsistence strategy of small-scale agriculture along with hunting and gathering. In their interpretation, a small number of families inhabited Shabik’eschee permanently, while others joined them periodically to take advantage of the site’s proximity to piñon woodlands in years with bountiful piñon-nut harvests. They based this theory on the presence of two types of storage facilities at the site: household-level storage in the antechambers associated with some but not all of the pithouses (presumably the residences of permanent residents) and community-level storage bins scattered around the site. The idea is that occasional surpluses of corn or whatever would be stored in the bins, and the people who lived at the site permanently watched over it and protected it. Whenever there was a plentiful crop of piñon nuts, which happens at irregular intervals in the fall, people who lived the rest of the time in scattered locations throughout the area would congregate at Shabik’eschee to take advantage of this and stay for the winter. If conditions in the spring were good for planting, people might stay longer and plant their crops in the area, but if not they would move on to more attractive planting locations. Other pithouse villages, such as 29SJ423, would presumably have served similar purposes, allowing periodic aggregation to take advantage of various localized resources.

This is an interesting theory, but it’s based on exceptionally thin evidence. Wills and Windes even concede that they are spinning this whole story purely from the nature of the storage facilities at the site, and they note that there are other ways to interpret the communal bins in particular. Instead of protecting food stores during periods of reduced occupation, they may just have functioned to protect them in general. The shape of the bins makes it more difficult to access their contents, which Wills and Windes interpret as evidence for a sort of semi-caching, but it would also just provide better protection from the elements, vermin, etc. for the contents. Basically, there’s just no reason from the available evidence to buy the Wills and Windes theory.

"Pithouse Life" Sign at Mesa Verde

Indeed, the assumptions behind this theory seem problematic to me. The ethnographic comparisons Wills and Windes use to support it are mostly from hunter-gatherer societies, and indeed their model seems to imply that the residents of Shabik’eschee were basically hunter-gatherers who did some farming on the side. Such societies exist, and may well have existed at certain times in the ancient Southwest (such as the late Archaic), but recent studies have shown with increasing certainty that heavy dependence on agriculture was widespread already in the Basketmaker II period. Wills and Windes seem to see the Basketmaker III inhabitants of the Chaco area as just beginning to experiment with adding agriculture to a hunter-gatherer lifeway, but it’s much more likely that they were full-time agriculturalists and had been for centuries. They did of course still do some hunting and gathering, as their Pueblo descendants have continued to do up to the present day, but while this may in some sense qualify as a “mixed” economy that shouldn’t obscure the important fact that Pueblo societies have been overwhelmingly farming-based societies since well before the occupation of Shabik’eschee.

I think this interpretation, and others like it which were popular in Southwestern archaeology in the 1980s, results in part from the enormous influence of Lewis Binford on the development of processual archaeology. Binford’s personal research and expertise were largely on hunter-gatherer societies, and the guidelines he set forth for “archaeology as anthropology” that were eagerly followed by young “New Archaeologists” were heavily influenced by that background. Wills and Windes cite Binford several times in this article.

Excavating the Lift Station Site in the Chaco Maintenance Yard

Be that as it may, this is an important article just in providing an updated take on the facts about Shabik’eschee, which as Wills and Windes note has been very important in the interpretation of ancient societies generally. It contains relatively little information about 29SJ423, but it does briefly discuss this site as a comparison. It says even less about the much more numerous isolated Basketmaker III sites in the canyon, but it notes that Chaco Project surveys identified at least 163 pithouse sites from this period. One that they didn’t find, because it was deeply buried under the ground, was later found by the park in the course of trying to build a lift station for the septic system. This site, informally known as the Lift Station Site, is a Basketmaker III pithouse that was excavated while I was working at Chaco. One of the more interesting things it revealed was an apparent location for pottery manufacture.

One of the major problems with trying to understand the Basketmaker III period at Chaco is precisely that the site are typically deeply buried, so it’s hard to even know how many of them there are. It’s clear that this was a period of significant population in the canyon, but it’s hard to tell how many sites were occupied simultaneously. This problem is exacerbated by the difficulty of dating many of the sites. Tree-ring dates are often hard to obtain from the scarce wood found at excavated sites, and Shabik’eschee is particularly poorly dated. The few tree-ring dates available seem to suggest it was occupied at some point after the mid-500s, but there are no cutting dates so any greater precision is impossible. 29SJ423 did produce two cutting dates, at 550 and 557, so it seems the two villages were most likely contemporaneous. The isolated sites are even harder to date, of course, but the Lift Station Site produced corn that was radiocarbon dated. I don’t know the dates that resulted, but I did hear that they were earlier than was expected based on the pottery types found.

Whole Pot from the Lift Station Site

The size of the Basketmaker III occupation at Chaco, and particularly the presence of the two large villages, has important implications for understanding the subsequent history of the canyon that I think are just beginning to be realized. The local population seems to have declined during the subsequent Pueblo I period (ca. AD 750 to 900), when people seem to have begun to move in large numbers to higher elevations where they formed some really large villages. However, it’s not clear that Chaco was completely abandoned during this period, and recent improvements in dating the early great houses in the canyon have shown that some of them, especially Pueblo Bonito, go back further than was once thought. Pueblo Bonito is now known to have been begun no later than 860, and the earliest part of it may date much earlier, possibly to 800 or even before. This means that the gap between the Basketmaker III villages and the earliest great houses suddenly looks a lot smaller, and may disappear entirely. There are pithouses under the plaza at Pueblo Bonito that may date to very early Pueblo I or even Basketmaker III, and there is a small Pueblo I occupation at Shabik’eschee that dates as late as 750. This suggests that these two iconic sites in Chacoan archaeology, generally interpreted in very different ways, may actually overlap in occupation. This would require some serious modifications of the ways the origins of the Chaco system are often interpreted.

Chaco had been an important place for a very long time when it started to become a major regional center around AD 1040. It’s looking increasingly plausible, though by no means certain, that it had been continuously occupied for 500 years at that point, and even if there was a brief gap between the Basketmaker III villages and the first Pueblo I great houses it is very unlikely that is was long enough for people to have forgotten about Chaco and what had happened there. Even if many of the people who built and/or occupied the early great houses in the 800s hadn’t been born at Chaco, they probably knew it was there long before they made it their home.Wills, W., & Windes, T. (1989). Evidence for Population Aggregation and Dispersal during the Basketmaker III Period in Chaco Canyon, New Mexico American Antiquity, 54 (2) DOI: 10.2307/281711

The “Chacoan era” is a period of about 100 years in the eleventh and early twelfth centuries AD during which Chaco Canyon was at the center of some sort of system that covered a large portion of the northern Southwest. The exact nature and exact extent of that system are endlessly debated, but the period during which it existed is fairly well-established. The exact dates given for the duration of the system vary among different researchers, and I’ve given various versions of them myself. Probably the most common ending date is AD 1130, which coincides both with the approximate end of apparent construction in the canyon and the onset of a 50-year drought that is generally thought to have had something to do with the decline of Chaco. To make it an even century, 1030 is a useful starting date for the Chacoan era, although it doesn’t actually correspond to anything special in the canyon as far as we can tell. A better starting date might be 1040, which is approximately when the expansion of Pueblo Bonito began, or 1020, which is about when construction began at Pueblo Alto. Using these starting dates with the hundred-year span gives ending dates of 1140 or 1120, which again are roughly equivalent to the end of major construction in the canyon. (It’s a lot easier to date the beginnings of phenomena in the ancient Southwest than the ends of them, due largely to the reliance on tree-ring dates.)

Whenever we say the Chacoan era began, it was long after the first great houses in Chaco Canyon were built. Indeed, the canyon had a long and probably very eventful history well before things really got going in the early 1000s. During the 900s it may not yet have been important on as large a scale as it became later but it was definitely already a place where things were happening. The origins of Chaco lie even earlier, however.

Type I and Type II Masonry Abutting at Peñasco Blanco

The first three great houses built in the canyon were Pueblo Bonito, Una Vida, and Peñasco Blanco. Una Vida is mostly unexcavated and Peñasco Blanco is completely so, so the dating of them relies mainly on tree-ring sampling of exposed wood. This has shown that these two sites probably date originally to the late 800s, with extensive expansion in the 900s. The earliest cutting date at Una Vida is from AD 861, while Peñasco Blanco has a cluster of cutting dates at AD 898. Both have clusters of dates in the 900s that suggest that much of the early construction dates to this period, and both also show expansion later, during the Chacoan era itself. Beyond that, though, not much can be said about the chronology of these sites.

Pueblo Bonito is a different story. It’s almost completely excavated, and while the excavation took place a long time ago, it left a lot more exposed wood than at most other sites. The recent Chaco Wood Project, which sought to sample every piece of exposed wood in the canyon to develop as full a chronology as possible, had its most spectacular results at Bonito. These were reported in part in an article in 1996 by Tom Windes and Dabney Ford, and the implications of the new dates for the architectural history of the site were more fully explained by Windes in a subsequent book chapter published in 2003.

Beams Sampled for Tree-Ring Dating in Room 227, Pueblo Bonito

To get a sense of the scale of this project, before it began in 1985 there were 163 pieces of wood from Pueblo Bonito that had been tree-ring dated. By the time the 1996 Windes and Ford article was published, this figure had risen to 4,294. That’s a big difference! We now have a much better idea of when different parts of Bonito were constructed, and that has shed important light on developments in the canyon at large and their relationship to events elsewhere in the Southwest.

Before this project, Pueblo Bonito was thought to have been initially constructed in the early 900s, with some reuse of beams from earlier structures accounting for a handful of dates in the 800s. This interpretation, expressed most influentially by Steve Lekson in his 1986 book on Chacoan architecture, was based largely on a tight cluster of cutting dates at AD 919 from Room 320 in the western part of “Old Bonito.” The enlarged sample, however, showed that it was actually this cluster that was a fluke, and that other beams from this wing produced dates in the mid-800s that more likely represent the initial construction of this part of the site. This seems particularly likely because the types of wood represented by these beams are largely piñon, juniper, and cottonwood, locally available species that were widely used early on, before the beginning of large-scale, long-distance procurement of large beams of ponderosa pine and other high-elevation woods. This suggests that the beams in Room 320 which dated to 919 were probably replacement beams rather than original construction. This block of rooms at the western end of Old Bonito was probably built around 860.

Room 320, Pueblo Bonito

Lekson thought this roomblock was probably the earliest part of the site. As it turns out, it was even older than he thought, but evidence from other parts of Old Bonito suggests that it was not actually the earliest part. A cluster of cutting dates at AD 891 in the northeast part of Old Bonito, which was clearly added onto the north-central part to the west of it, suggests that it was the north-central part that was actually first. This makes sense just from looking at the plan of the rooms, actually. This part of the site is less regular and formal in organization than the east and west wings of Old Bonito, and since it lies between them it seems logical that they would have been added on to the original central room suites. This is a bit hard to interpret, however, since the places where these different parts of the Old Bonito arc would have come together are mostly buried under complicated later construction.

Windes suggests in his 2003 paper that the very oldest part of the site was the block consisting of Rooms 1, 2, 4/5, 6, 35, 36, 37, and 61. None of these rooms produced wood that could be dated. Room 6 contains a considerable amount of original wood, which can be seen today under a modern roof put on to protect it, but this is mostly cottonwood, which is very difficult to date. As noted above, however, the use of local types of wood like cottonwood is a characteristic of very early construction at Chaco, so even though these beams couldn’t be dated they do still provide some evidence that this part of the site is very early. The western roomblock, dating to around 860, was probably added onto this one. This implies that the north-central block predates 860, and Windes says it is “probably much earlier” even than that (although he doesn’t explain why he thinks this).

Intact Roof Beams in Room 6, Pueblo Bonito

How much earlier? It’s hard to say. The earliest cutting date at Bonito is 828, from Room 317 in the western roomblock, which both Lekson in 1986 and Windes and Ford ten years later considered likely to be a reused beam. Since the overall distribution of dates in this block suggests construction around 860, this is probably right, and it’s hard to say where the beam would have come from. Probably not the north-central roomblock, which would probably have still been in use in 860. Interestingly, this beam is of ponderosa pine.

The north-central roomblock could well date to around 800 or even earlier, and that brings us to an interesting point. There are a bunch of pitstructures buried deep under later construction in what would have been the original plaza of Old Bonito; these were not extensively excavated, but they probably correspond to the room suites that make up Old Bonito and therefore date to the 800s. There are two even earlier pitstructures, however, further south in the later plaza of the expanded Bonito. Neil Judd, who excavated the site in the 1920s, didn’t pay much attention to them because he thought they were too early to have anything to do with Pueblo Bonito itself. They apparently date to the Pueblo I or late Basketmaker III period. Back when the consensus was the Bonito itself wasn’t built until 919, it made sense to agree with Judd that these pithouses were too early, but now that we know that the earliest parts of Old Bonito date well back into Pueblo I it starts to look more plausible that there is actually some continuity here. Since Judd didn’t look very closely at the early pithouses, we have no way of dating them, which is unfortunate, but one possibility that is looking increasingly plausible is that there was no hiatus at all between the occupation of those pithouses and the earliest occupation of Old Bonito. In that case, Pueblo Bonito as an important, inhabited location (rather than as the building we see today) might actually date back to Basketmaker III. And, importantly, whoever lived there at that time wouldn’t have been alone in the canyon. But that’s an issue for another post.Windes, T., & Ford, D. (1996). The Chaco Wood Project: The Chronometric Reappraisal of Pueblo Bonito American Antiquity, 61 (2) DOI: 10.2307/282427

Returning to my theory that the large square rooms with hearths and other residential features found at some great houses in Chaco and elsewhere were in some sense replacements for earlier kivas, I think the best evidence for this at Chaco itself (as opposed to at outlying great houses like Salmon) comes not from Pueblo Bonito, which is just too complicated a palimpsest to make something like this easy to see, but from the other early great houses: Una Vida and Peñasco Blanco. These at least seem to have simpler layouts than Bonito, though the extent to which this is just an effect of their being (mostly) unexcavated is unclear. Nevertheless, at least some parts of these two great houses do seem to show basically the pattern that I’m proposing for the development of residential room suites at great houses.

To recap the idea: The very earliest great houses, those built in the AD 800s, seem to show a pattern of suites similar to that seen at small houses or unit pueblos, with each suite consisting of one rectangular room backed by two smaller rooms. In front of each roomblock there are subterranean kivas, usually with slightly fewer than would be expected if each suite had its own kiva. This suggests to me that the suites housed individual nuclear families, but that they were grouped into larger units, perhaps extended families, which shared kivas. Whatever rituals these residential units would have conducted would probably have been in the kivas, but for the most part these were still residential structures, similar to the pithouses occupied in earlier centuries but with some of their functions transferred to the rectangular front rooms of the roomblocks. The smaller rooms in the back would have been used for storage. A typical great house would contain a few of these suites, with a kiva for every two or three. It’s unclear what the relationships among different kiva-units within a great house would have been, but they could have either been separate extended families within the same real or fictitious “clan” or “lineage,” or they could have been separate lineages that were politically or ceremonially allied. Importantly, all of these buildings are still residential at this point, although the residents may well host rituals or feasts open to the whole community either to solidify their political authority or because generosity is expected of them in exchange for community acceptance of their greater wealth or political/religious authority. The main difference between great houses and small houses is just that great houses are bigger, with multiple stories in some instances and generally bigger rooms, as well as more extensive use of masonry rather than adobe or jacal construction.

Room 330, Pueblo Bonito

Then, at some point in the 900s, a change takes place in some (all?) great houses. Use of the kivas is discontinued, and instead the activities that had been conducted in them are transferred to square surface rooms added onto the existing roomblocks. This definitely seems to be what happens at Una Vida and Peñasco Blanco, although the extent to which there were earlier kivas is unclear given the lack of excavation. In great houses newly begun during this time (it’s unclear how many of these there were in Chaco itself, but Kin Nahasbas may be an example), room suites were built without any kivas but with large, square rooms in front and smaller rectangular rooms varying in number behind them for storage. This pattern continues well into the 1000s, at least at some great houses, and it’s associated with the very formal, symmetrical, rectilinear layout seen at sites such as Hungo Pavi, Chetro Ketl, and Pueblo Alto. Some outlying great houses, such as Kin Bineola and (especially) Salmon, show this pattern as well. Salmon seems to show that new great houses with (almost?) exclusively square rather than round living rooms were still being built as late as 1090, and if the early construction at Aztec is in the same pattern, which seems to be a matter of some dispute, it would still be going on well into the early 1100s. This is probably also what we see at Pueblo Bonito too, with the possible addition of square rooms like 329 and 330 to the older suites at the west end of Old Bonito and the later addition of linear suites to the south of these rooms at the southwest corner of the site.

At some point in the late 1000s, however, a different type of room suite begins to arise at some Chaco great houses. This is still a linear suite, sort of, but it consists of a round kiva built aboveground into a first-story square room, with one or two rows of two- or three-story rectangular rooms extending back from it. These are the “blocked-in” kivas that are probably the most famous innovation of Chacoan architecture. I see them as still residential spaces, in combination with the rooms behind them. Their appearance at most outlying great houses indicates residential use of those sites, perhaps by local elites. It’s not clear what the relationship is between these plaza-facing blocked-in kiva suites and the “elevated” kivas surrounded by rectangular rooms that start to appear at the centers of the rectilinear great houses with the square living rooms around this same time. If those rooms are still residential, they’re pretty damn fancy residences. They’re also quite unlike the other residential rooms at these sites, which are still square. The “Tower Kiva” at Salmon is one example, as are the corresponding kiva at Hungo Pavi and the numerous examples at Chetro Ketl. The central placement and unusual elaboration of these structures has led many to assume that they were ceremonial rather than residential in function, but I’m not so sure. These sites do generally have great kivas, which pretty much everyone agrees were community-scale ceremonial/integrative structures, and they look quite different from elevated kivas (although it’s not clear to what extent the unique features of great kivas are due to structural requirements following from their size).

Kivas in the Southeast Part of Pueblo Bonito

In any case, the best examples of the plaza-facing blocked-in kiva suites are at Pueblo Bonito in the southeast and southwest wings. These appear to have been built over earlier construction, so it’s not totally clear what was going on with these multiple, quite rapid changes in site layout during this period. Again, though, they’re also obvious at Una Vida and Peñasco Blanco, where some (but not all!) of the earlier square living rooms are replaced by blocked-in kivas. This also appears to have happened in the west wing of Chetro Ketl, but it’s unexcavated so it’s hard to say for sure. There definitely are two blocked-in kivas there, though, and they appear to have rooms behind them like at Pueblo Bonito.

Then, at some point toward the very end of the eleventh century or very early in the twelfth, a totally new type of room suite begins to appear at Chaco great houses. This is the famous “McElmo unit,” with a central blocked-in kiva surrounded on three or four sides by rectangular rooms, most of them significantly higher (three or four stories), creating a sort of “patio” over the kiva. These rarely have ground-floor exterior walls, and they are remarkably uniform and modular in form. The most famous of these structures are the freestanding ones, including New Alto, Casa Chiquita, and Kin Kletso (which comprises two adjacent units), but clearly analogous forms can be seen within certain great houses, including the north and south wings of Pueblo del Arroyo and the Kiva B complex at Pueblo Bonito. Similar units that are just outside of existing great houses can be seen at Chetro Ketl and Peñasco Blanco. The masonry of most of these is very different from that used at earlier great houses, being composed of blocky yellow sandstone rather than fine, hard, dark sandstone, and this has been used to argue that they represent influence from the north. The masonry may indeed reflect northern influence (though in a different way from what the original proposers of this idea thought), but the form predates the shift in masonry and probably developed locally in Chaco.

Kiva E, Kin Kletso

There has been a lot of debate over the function of McElmo units. Some see them as warehouses, while others see them as ritual (or possibly astronomical) special-use sites. I’m increasingly thinking that all this speculation is based on an overemphasis on their differences from earlier great houses, and that they were probably residential and represent the final version of the Chacoan room suite. More on this later.

McElmo units may represent the final development of Chacoan architecture in terms of form, but the great houses continued to be occupied for quite some time after the construction of these roomblocks in the early 1100s. What we see at this point is an increased emphasis on the blocked-in kiva concept, with new kivas, often of “non-Chacoan” form, being built into earlier square or rectangular rooms. Some call these “intra-mural” rather than “blocked-in” kivas, to emphasize that they were built into earlier rooms rather than having square rooms built around them, and I think this is a helpful distinction. These really proliferate at Pueblo Bonito late in the occupation period, and this also happens at Aztec and Salmon during their “post-Chacoan” (also called “secondary” or “Mesa Verdean”) occupations. At the same time, many great houses also see the construction of new subterranean kivas in the plazas, often with accompanying small blocks of square rooms. These aren’t usually datable directly, but they appear to be very late. Pueblo Bonito has particularly many of these, and there are a few in the southeast corner of Chetro Ketl too. These appear to represent the construction of typical small-house or unit-pueblo style residential units within earlier great houses, and they may or may not represent an occupational discontinuity of some sort.

So basically, what we see is a sequence of underground kiva to above-ground square room to above-ground kiva. There are plenty of variations and complications, but that’s the general sequence. The later use of intra-mural kivas, especially at Pueblo Bonito, has tended to obscure the middle stage here, but it really seems to represent something meaningful at least as a chronological marker in Chacoan architecture. Does it mean anything else culturally? That part I’m still looking into, but it may.